Membranes are known which include a reinforcement having an asphaltic based coating thereon and including a pressure-sensitive adhesive on one side thereof. These membranes have utility for waterproofing purposes and for highway repair and maintenance purposes. U.S. Pat. Nos. 3,741,856 and 3,900,102 exemplifies such membranes. Such membranes are also commercially available under the trade designation Bituthene waterproofing membrances. It is believed that the pressure-sensitive adhesives employed in such membranes are admixtures of a rubber and an asphalt.
The above-incorporated co-pending applications also disclose such highway repair and maintenance membranes in the form of a laminate comprising a membrane of an asphaltic based composition coated fibrous reinforcement material and having an adhesive layer on one side thereof adapted to adhere to cementitious substrates, like Portland Cement and asphaltic cement. The asphaltic-based coating is a substantially non-tacky reaction product of asphalt, a polymerizable vinyl aromatic monomer, a non-depolymerized rubber, a terpene resin, and a depolymerized rubber, i.e., rubber which has been treated with a depolymerizing agent to decrease its molecular weight.
The present invention provides for asphaltic based, pressure-sensitive adhesives which may be employed in the above type indicated membranes or laminates, with the adhesive being prepared by hot melt blending a mixture consisting essentially of an AC-20 paving grade asphalt having a penetration of about 40 to about 65 and a viscosity of about 160,000 to about 240,000 cps at 140.degree. F., a depolymerized virgin rubber, a terpene resin, and a vulcanizable, non-depolymerized styrene-butadiene copolymer. Relative to the preseure-sensitive adhesive described in the above-incorporated applications, the present adhesives are manufactured much more economically, that is, in shorter periods of time because the present adhesives are formed by simply hot melt blending the ingredients as opposed to performing a chemical reaction. Additionally, the formulations of the present invention eliminate one of the significant consitutents of the above-indicated pressure-sensitive adhesives which are prepared by a reaction and thereby also results in lower manufacturing costs.